This invention relates to angiography and more specifically, the injector used to inject a medical fluid such as radiographic contrast material into living organisms.
One of the major systems in the human body is the circulatory system. The major components of the circulatory system are the heart, blood vessels, and the blood, all of which are vital to the transportation of materials between the external environment and the different cells and tissues of the human body.
The blood vessels are the network of passageways through which the blood travels in the human body. Specifically, arteries carry the oxygenated blood away from the left ventricle of the heart. These arteries are aligned in progressively decreasing diameter and pressure capability from the aorta, which carries the blood immediately out of the heart to other major arteries, to smaller arteries, to arterioles, and finally to tiny capillaries, which feed the cells and tissues of the human body. Similarly, veins carry the oxygen-depleted blood back to the right atrium of the heart using a progressively increasing diameter network of venules and veins.
If the heart chambers, valves, arteries, veins or other capillaries connected thereto are either abnormal (such as from a birth defect), restricted (such as from atherosclerotic plaque buildup), or deteriorating (such as from aneurysm formation), then a physician may need to examine the heart and connected network of vessels. The physician may also need to correct any problems encountered during the examination with a catheter or similar medical instrument.
Angiography is a procedure used in the detection and treatment of abnormalities or restrictions in blood vessels. During angiography, a radiographic image of a vascular structure is obtained by injecting radiographic contrast material through a catheter into a vein or artery. The vascular structures fluidly connected with the vein or artery in which the injection occurred are filled with contrast material. X-rays are passed through the region of the body in which the contrast, material was injected. The X-rays are absorbed by the contrast material, causing a radiographic outline or image of the blood vessel containing the contrast material. The x-ray images of the blood vessels filled with contrast material are usually recorded onto film or videotape and are displayed on a fluoroscope monitor.
Angiography gives the doctor an image of the vascular structures in question. This image may be used solely for diagnostic purposes, or the image may be used during a procedure such as angioplasty where a balloon is inserted into the vascular system and inflated to open a stenosis caused by atherosclerotic plaque buildup.
Currently, during angiography, after a physician places a catheter into a vein or artery (by direct insertion into the vessel or through a skin puncture site), the angiographic catheter is connected to either a manual or an automatic contrast injection mechanism.
A simple manual contrast injection mechanism typically has a syringe and a catheter connection. The syringe includes a chamber with a plunger therein. Radiographic contrast material is suctioned into the chamber. Any air is removed by actuating the plunger while the catheter connection is facing upward so that any air, which floats on the radiographic contrast material, is ejected from the chamber into the air. The catheter connection is then attached to a catheter that is positioned in a vein or artery in the patient.
The plunger is manually actuated to eject the radiographic contrast material from the chamber, through the catheter, and into a vein or artery. The user of the manual contrast injection mechanism may adjust the rate and volume of injection by altering the manual actuation force applied to the plunger.
Often, more than one type of fluid injection is desired, such as a saline flush followed by the radiographic contrast material. One of the most common manual injection mechanisms used today includes a valve mechanism which controls which of the fluids will flow into the valving mechanism and out to the catheter within the patient. The valve mechanism contains a plurality of manual valves that the user operates manually to open and close that particular fluid channel. When the user suctions or injects contrast fluid into the chamber, the fluid is pulled from the valve mechanism via the open valves. By changing the valve positions, another fluid may be injected.
These manual injection mechanisms are typically hand actuated. This allows user control over the quantity and pressure of the injection. However, all of the manual systems are only capable of injecting the radiographic contrast material at maximum pressure that can be applied by the human hand (i.e., 150 p.s.i). Also, the quantity of radiographic contrast material is typically limited to a maximum of about 12 cc. Finally, there are no safety limits on these manual contrast injection mechanisms which act to restrict or stop injections that are outside of reasonable parameters (such as rate or pressure) and no active sensors to detect air bubbles or other hazards.
Currently used motorized injection devices consist of a syringe connected to a linear actuator. The linear actuator is connected to a motor, which is controlled electronically. The operator enters into the electronic control a fixed volume of contrast material to be injected at a fixed rate of injection. The fixed rate of injection consists of a specified initial rate of flow increase and a final rate of injection until the entire volume of contrast material is injected. There is no interactive control between the operator and machine, except to start or stop the injection. Any change in flow rate must occur by stopping the machine and resetting the parameters.
The lack of ability to vary the rate of injection during the injection results in suboptimal quality of angiographic studies. This is because the optimal flow rate of injections varies considerably between patients. In the cardiovascular system, the rate and volume of contrast injection is dependent on the size of and blood flow rate within the chamber or blood vessel being injected. In many or most cases, these parameters are not known precisely. Moreover, the optimal rate of injection can change rapidly, as the patient""s condition changes in response to drugs, illness, or normal physiology. Consequently, the initial injection of contrast material may be insufficient in flow rate to outline the structure on x-ray imaging, necessitating another injection. Conversely, an excessive flow rate might injure the chamber or blood vessel being injected, cause the catheter to be displaced (from the jet of contrast material exiting the catheter tip), or lead to toxic effects from contrast overdose (such as abnormal heart rhythm).
At present, the operator can choose between two systems for injecting contrast material: a manual injection system which allows for a variable, operator interactive flow rate of limited flow rate and a preprogrammed motorized system without operator interactive feedback (other than the operator can start/stop the procedure).
The invention described in Ser. No. 08/426,149 is a dual port syringe used to deliver medical fluids such as angiographic radiographic contrast material to a patient. The dual port syringe includes a syringe body, a piston which is reciprocally movable in the syringe body, and upper and lower parts.
The upper port is connected to a fluid reservoir so that medical fluid is drawn from the fluid reservoir through the upper port into the syringe body when the piston moves in a rearward direction. The lower port is connected to a device, such as a catheter, through which the medical fluid is delivered under pressure to the patient. When the piston moves in a forward direction, medical fluid is delivered under pressure out of the syringe body through the lower port.
In preferred embodiments, the first valve is connected between the fluid reservoir and the upper port, and a second valve is connected between the lower port and patient. The first valve permits flow of fluid from the fluid reservoir to the upper port when the piston moves rearwardly and air to be expelled when the piston moves forwardly. The second valve permits flow of material out of the lower port when the piston moves in a forward direction.
The present invention comprises a syringe for use in a angiographic injector of a type having a syringe holder. The syringe includes a syringe body having a distal end and a proximal end. The syringe body defines a pumping chamber and an inlet port. A syringe end wall is located at the distal end of the syringe body and has a flat face for mating engagement with the syringe holder. The end wall defines an outlet port. A syringe plunger is located in the pumping chamber and is adapted for reciprocal motion between a position proximate to the proximal end and the distal end.
Preferably, the syringe end wall defines an interior portion and an exterior portion. The exterior portion defines the flat face. In preferred embodiments, the exterior portion is reinforced with a plurality of ribs. The ribs each have end portions terminating in a plane transverse to a longitudinal axis of the syringe body. The end portions of the ribs define the flat face. Preferably, the interior portion defines a cone-shaped surface.
In one preferred arrangement, the syringe body defines a top portion. The inlet port is located in the top portion.
Preferably, the end wall defines a first portion and a second portion. The first portion is adjacent to the top portion of the syringe body, and the second portion is adjacent to an end of the end wall opposite of the first portion. The outlet port is preferably located in the second portion of the end wall.
Preferably, a valve arrangement is constructed and arranged to prevent liquid from flowing out of the pumping chamber through the inlet port when the plunger moves from the proximal end to the distal end.
In another aspect, the invention is directed to an injection system comprising a syringe and a syringe holder arrangement. The syringe includes a barrel defining a pumping chamber, a longitudinal axis, and at least one port for providing fluid flow communication with the pumping chamber. The barrel has a distal end and a proximal end. The distal end includes a flat wall section normal to the central longitudinal axis. The syringe includes a plunger constructed and arranged within the pumping chamber for reciprocal motion between a position adjacent to the proximal end and the distal end. The syringe holder arrangement includes a mounting chamber body and door member. The mounting chamber body is constructed and arranged to hold the syringe, and it includes a loading end for receipt of the syringe. The door member is movable relative to the body to allow for selective opening and closing of the loading end of the mounting chamber body. The door member defines a flat, planar surface for abutting engagement with the flat wall section of the syringe.
Preferably, the syringe includes an inlet port and an outlet port. The outlet port is preferably defined by the flat wall section. The syringe includes an inlet port housing surrounding the inlet port, and an outlet port housing surrounding the outlet port. The outlet port housing projects from the flat wall section.
Preferably, the door member defines a slot for slidable communication with the outlet port housing. That is, as the door member rotates into a closed position, the outlet port housing slides in the slot.
In one preferred embodiment, the syringe holder arrangement further includes a pressure containment sleeve selectively mounted within the mounting chamber body for slidable receipt of the syringe. The pressure containment sleeve defines open first and second, opposite ends. The first end is adjacent to the loading end of the mounting chamber body. The door member is selectively movable to open and close the first end.
Preferably, the pressure containment sleeve defines an open channel for slidable communication with the inlet port housing.
In preferred arrangements, the syringe holder arrangement further includes a plate mounted in covering relation to the second end of the pressure containment sleeve. The plate defines an aperture for allowing manipulation of the syringe plunger, when the syringe is positioned in the pressure containment sleeve. Preferably, the syringe holder arrangement further includes a bottle-holder assembly constructed and arranged to mount a bottle in fluid flow communication with the inlet port housing.
In another aspect, the invention is directed to a method for mounting a syringe. The method comprises a step of first, positioning a syringe through a front aperture in a syringe holder arrangement. After the step of positioning a syringe, the method includes pivoting a door of the syringe holder arrangement to close the front aperture and abut a front face of the syringe.
Preferably, the step of positioning a syringe includes providing a syringe having a first end at the syringe front face and defining a fluid port, and a second end slidably receiving a plunger. The step of positioning includes orienting the syringe through the front aperture such that the second end passes through the front aperture followed by the first end.
In one preferred method, the step of positioning a syringe includes inserting the syringe into an interior of a pressure containment sleeve.
Preferably, the front face of the syringe is planar with an outlet port housing extending therefrom surrounding the fluid port, and the door includes a planar surface. The step of pivoting a door includes sliding the planar surface of the door relative to the planar, front face of the syringe.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.